Dennis joined The Elders in September 2023 as a Senior Programme Advisor on Conflict. Before this, he worked in a number of countries and headquarters posts with UNDP, the UK Department for International Development / Foreign Commonwealth and Development Office, and international Non-Governmental Organisations. His work has spanned peacebuilding, democratic governance, human rights and humanitarian response.

Dennis holds a Masters degree in Development Studies from University College Dublin and a Masters and BA in Mathematics from Trinity College Dublin. He lives with his wife, daughter and son in North London and enjoys trail running and playing music, mainly guitar and fiddle.